wml tools GUI: exclude the double endline at the end of the file when exporting as text

data/tools/GUI.pyw

@@ -1138,7 +1138,7 @@ Error code: {1}""".format(queue_item[0],queue_item[1]))
         if fn:
             try:
                 out=codecs.open(fn,"w","utf-8")
-                out.write(self.text.get(1.0,END))
+                out.write(self.text.get(1.0,END)[:-1]) # exclude the double endline at the end
                 out.close()
             except IOError as error: # in case that we attempt to write without permissions
                 showerror("Error","""Error while writing to: